There are two main types of fixed connections used in various industries:

• Detachable - using threaded fasteners: bolts, nuts, studs and screws;
• One-piece - performed by welding, gluing, riveting, soldering.

The named types of fasteners are used in all branches of mechanical engineering, and these works account for about 35% total costs labor. The range of fasteners used is very large and is constantly expanding, since new, more advanced and expensive equipment is constantly being put into operation, the production of which requires the use of more reliable and durable connections, which, among other things, must correspond to the aesthetic level of the equipment.

In the state classification, fasteners used in mechanical engineering belong to the GZ group, in which the following subgroups are distinguished: G31 (bolts); G32 (screws, studs); GZZ (nuts); G34 (rivets); G36 (washers, cotter pins); G37 (pins); G38 (other industrial hardware). On this moment many modern and progressive types of fasteners, actively used in mechanical engineering, are not included in the Classifier state standards. The wide variety of fasteners, different in design and manufacturability, greatly complicates their description and determination of belonging to one class or another. Despite the existing difficulties, fasteners can be divided into five main groups according to one most characteristic feature, which underlies the name of each group:

• widely used fasteners;
• fasteners for joining polymer composite materials;
• high strength threaded fasteners;
• fasteners for high-life and hermetic connections;
• fasteners for one-sided mounting and impact-free riveting.

This classification is rather arbitrary, since many types of fasteners can be classified into different groups due to their versatility. At the same time, each group includes fasteners belonging to different classes, according to the Classifier of State Standards. For example, the group of high-strength threaded fasteners includes screws, bolts and nuts, and the classes of bolts and rivets are included in the group of high-resource fasteners.

The described classification helps workers in technical and design departments to freely navigate a wide variety of fastening tools and apply the necessary elements in each specific case, developing optimal designs mechanical engineering with reliable fastenings. This classification is also convenient for designers of various types of fasteners.

It is quite difficult to give the correct name to the fastener due to such diversity. In order to understand the types of fasteners, it is better to refer to the terminology according to GOST. Below we will consider the most commonly used definitions of fasteners, corresponding to GOST 27017-86.

General concepts
Fastener type	Part for forming a connection.
Bolt	Rod shaped fastener with external thread at one end, with a head at the other, forming a connection by means of a nut or threaded hole in one of the products being connected.
Screw	A fastener for forming a connection or fixation, made in the form of a rod with an external thread at one end and a structural element for transmitting torque at the other. Note: The structural element of the screw for transmitting torque can be a slotted head, a knurled head, or, in the absence of a head, a slot in the end of the rod.
Screw	A fastener in the form of a rod with an external special thread, a threaded conical end and a head at the other end, forming a thread in the hole of the wooden or plastic product being connected. Note: The special thread has a triangular, pointed profile and a larger cavity width compared to the width of the tooth.
Hairpin	A fastener in the form of a cylindrical rod with male threads on both ends or the entire length of the rod.
Pin	A fastener in the form of a cylindrical or conical rod for fixing products during assembly.
screw	Fastener with threaded hole and a structural element for transmitting torque. Note: The structural element of the nut for transmitting torque can be a polyhedron, knurling on the side surface, end and radial holes, splines, etc.
Washer	A fastener with a hole placed under a nut or the head of a bolt or screw to increase the bearing surface and/or prevent them from self-unscrewing.
Cotter pin	A fastener in the form of a semicircular wire rod, folded in half to form a head.
Rivet	A fastener in the form of a smooth cylindrical rod with a head at one end, used to obtain a permanent connection due to the formation of a head at the other end of the rod by plastic deformation.

Types of fasteners
Step bolt	A bolt whose diameter of the smooth part of the rod exceeds the nominal diameter of the thread.
Hinge bolt	A bolt whose head is made in the form of a movable part of a hinge joint.
Fit bolt Unacceptable: Bolt for reamer hole	A bolt, the diameter of the smooth part of the rod is determined from the condition of ensuring the operation of the shear connection.
Foundation bolt	A bolt with a specially shaped head used to secure equipment to the foundation. Note: The special shape of the head can represent the spread legs of the slotted part of the rod, the bent part of the rod, etc.
Captive screw	A screw whose diameter of the smooth part of the rod is smaller internal diameter threads.
Self tapping screw	A screw that forms a special thread in a hole in one of the plastic or metal products being connected.
Self Drilling Self Tapping Screw	Self-tapping screw with drill shaped end.
Set screw	A screw with a specially shaped end that serves to fix products relative to each other. Note: The special end shape can be cylindrical, conical, flat, etc.
Spring pin	A cylindrical pin with a longitudinal groove along its length, made of spring steel.
Slotted nut	Hexagonal nut with radially located slots for a cotter pin on the side of one of the end surfaces.
Castle nut	A hex nut, part of which is made in the form of a cylinder with radially located slots for a cotter pin.
Cap nut	Nut with spherical and flat end surfaces and a blind threaded hole.
Wing nut	A nut with flat protruding elements for transmitting torque.
Flat washer	Washer with a flat supporting surface.
Spring washer	A split round washer, the ends of which are located in different planes, which serves to prevent self-unscrewing of fasteners during its elastic deformation under load.
Lock washer	A washer used to prevent self-unscrewing of fasteners using structural elements. Note: Structural elements washers are tabs, toes, teeth, etc.
Hollow rivet	Rivet with a tubular cross-section rod.
Semi-hollow rivet	A rivet, the end part of the shaft of which has a tubular cross-section.

Fastening elements
Fastener rod Kernel	Part of a fastener that fits directly into the holes of the products being connected or is screwed into the material of one of them.
Fastener head Head	Part of a fastener having a shaft that serves to transmit torque and/or form a bearing surface.
Bolt head Subhead	The smooth portion of a bolt's shank, cylindrical, oval, or square, directly adjacent to the head and used to center the bolt or prevent it from turning.
Fastener collar Burt Unacceptable Flange	A protrusion on the supporting surface of a multifaceted nut, bolt head or screw, made in the shape of a cylinder or truncated cone with a diameter greater than the diameter of their circumscribed circle.
Fastener support lug Support ledge Unacceptable Support washer "Dead Puck"	An annular projection on the bearing surface of a polygonal nut or bolt head, the diameter of which smaller size Full construction. Note: The key size is understood as the distance between the opposite edges of a multifaceted nut or bolt head, screw, measured in a plane normal to their axis.
Fastener spline Slot	A specially shaped recess at the end of the head of a bolt, screw or screw, at the end of a set screw without a head, along a generatrix or at the end of a nut. Note: The shape of the slot can be hexagonal, cross-shaped, in the form of a through or non-through slot, etc.
Bolt tenon Thorn	A protrusion on the supporting surface of the bolt head that serves to prevent it from turning.
Bolt tab Us	A protrusion on the supporting surface of the head and shank of a bolt, which serves to prevent it from turning.
Gimlet	The threaded, conical end of a screw used to cut threads into a piece of wood or plastic to form a joint.

GOST 27017-86 fully complies with the requirements of the ISO 1891-79 standard and provides terminological definitions of fasteners used in mechanical engineering. The standards specify only basic terms. But the process of the emergence of new types of fasteners on Russian market does not stop, so the addition of terminology is constant. At the same time, all market participants want the adoption of standardized terminology to prevent discrepancies.

This article uses materials from the site http://www.kvadromet.ru/article/a013.html

When performing a wide range of repair and construction work, it is impossible to do without the use of various fasteners. On modern construction market There is a wide range of these products that are necessary for high-quality solutions to various technical and technological problems. Their functional purpose can be completely different - from fixing a board with a simple nail, to installing an anchor that must withstand increased operating loads.

This material will discuss the main types of fasteners, various classifications, GOSTs, markings and areas of their application. They come in a wide variety of shapes, sizes and purposes - the most common today are:

• nuts;
• dowels;
• anchors;
• screws;
• self-tapping screws;
• rivets;
• hairpins;
• washers and others.

Depending on the thread pitch, fasteners are metric or non-metric (adapted).

In addition, there is another classification of fasteners - it is based on other criteria. According to it, these elements are:

• threaded, increased strength;
• fasteners for mass use;
• fasteners for shockless fixation and one-sided installation;
• elements for hermetic structures;
• fasteners necessary for fastening polymer composite materials.

This classification, although it significantly simplifies the sorting process, is conditional, since elements of one group may also belong to another. Let's take a closer look at the main ones.

Nails

Perhaps today there is no master who would not use nails in the process of his work. This is the most ancient and widespread fastening material today, which is widely used in many industries. economic activity person. The material of their production is usually steel or steel types of wire. The nail marking consists of two numbers:

• rod diameter;
• its length (in mm).

The heads of these elements can be either smooth or corrugated, and screw and club nails can have helical, longitudinal and transverse grooves, burrs or dents on the shaft. Such products provide significant resistance to pull-out processes.

Depending on the technical characteristics material, the scope of use of nails also differs. For example, hardened steel products can be safely driven into brick or concrete walls. However, when working with them, you should pay attention to the high fragility of this material. In order to attach them to hard surfaces, it is necessary to use wallpaper, roofing felt and plaster types of nails. They are produced with flatter and wider caps than usual, as well as shorter stems. In conditions aggressive environment Copper nails can be used, which are practically not subject to corrosion processes, as well as galvanized nails or alloy steel products.

As for the technological features of driving nails, they also have their own specifics. These processes require taking into account certain nuances, so we recommend using our professional advice:

• to prevent the occurrence of dents while driving nails, it is necessary to use a countersink;
• to ensure fixation strength, the fastening rod must be at least 2/3 of the length included in the lower fixed part;
• when driving small nails, it is best to use special auxiliary accessories;
• To increase the strength of joints, nails should be driven in at an angle rather than straight. The same applies if you need to hang something on it;
• if the nail went through the wall when driving, it should be carefully bent and polished using a triangular file;
• to prevent damage to surfaces when pulled out with pliers, you simply need to place a plate under them that reduces the pressure;
• if in the future it is planned to dismantle parts, then better than nails do not use at all, preferring screws.

Very often, liquid nails can be used during the work process. They are made of polymer materials and rubber and are able to provide adequate fastener strength indicators no worse than traditional nails. One drop of such a substance can withstand up to 50 kg of load, but their main advantage is the complete preservation of the integrity of decorative surfaces.

Scope of use liquid nails very wide. They are used for fixation various panels, plasterboard, chipboard, fiberboard, plywood, cardboard, ceramics, stone, stucco, glass and much more. However, when choosing these fasteners, it is necessary to pay special attention to adhesion indicators, since different types materials have varying degrees. They are most appropriate to use when:

• temperature not lower than -90 С;
• high room humidity.

For example, some types of neutral nails are harmless because they are based on water, but they are not suitable for gluing metal. Liquid nails based on organic solvents have a high setting speed and are able to withstand exposure temperature regime up to -25 С. Their only disadvantage is the presence of harmful volatile components that emit unpleasant odors for 5 days.

The setting of such nails occurs within 10-40 minutes, depending on the type and marking, but complete polymerization occurs only after 24 hours.

Self-tapping screws

Self-tapping screws also occupy a special niche among fasteners. There are not so many varieties of them on the modern market - a full classification is possible only according to 3 main criteria - the material into which they are screwed, size and functional purpose. According to the first criterion, the following types of self-tapping screws are distinguished:

• for metal;
• for wood.

Both products can have different lengths, widths, diameters, as well as different steps threads. Typically, self-tapping screws for metal surfaces have a fine thread pitch, unlike “wooden” ones, which have a larger thread pitch.

Products for metal can be of several types - self-tapping and those that require preliminary drilling of the metal. The first type has a special drill at the tip, the size of which indicates the thickness of the metal into which it needs to be screwed. An example of such self-tapping screws are tex, which are used to fix gypsum plasterboard profiles. As for their second subgroup, it includes black self-tapping screws, which are necessary for attaching gypsum boards to the metal profile.

In addition, the classification of self-tapping screws can also be carried out according to their functional purpose. For example, there are self-tapping screws for roofing and general purpose. Roofing ones have a wide cap with a press washer, which is necessary to seal the hole to prevent water leakage.

Anchors: types and features of application

An anchor is a fastening element that is designed to fix various designs and materials. In addition, this name characterizes parts partially concreted into any concrete product. Depending on the design, shape and purpose, the following types of anchors are distinguished:

• ceiling;
• driving;
• wedge;
• frame;
• anchors with half rings and rings;
• anchors with nuts.

They are united by a common function - fastening. For example, drive-in anchors with internal type threads and a cone-shaped wedge are necessary in order to fix various products and materials for a brick or concrete base. It is installed quite simply: it is fixed into a pre-made hole. Its radius and depth are selected depending on the size of the anchors themselves.

Wedge-shaped products are used for rapid fastening of planks, profiles, suspended ceilings. These types of anchors are very often used for fixation heavy equipment on a solid base. For high-quality installation wedge anchors, a hole is drilled in the concrete base into which the product is hammered using a hammer, which is subsequently tightened with nuts. As for ceiling anchors, they can be made of galvanized steel, and are necessary for fixing metal profiles, facades, railings, gratings and other products on concrete or stone base without the appearance of cracks. Frame anchors are necessary for attaching frames and wooden door frames to concrete walls.

A lot of users try to use this type of fastener for other purposes. For example, they are attached to brick walls, as a result of which the fastening element and nerves deteriorate. But the main thing is the very large holes that remain in the brick after the anchor is removed. They are usually used in concrete materials, while in soft ones such bolts tend to simply scroll. Classification of anchors is also a very difficult task, since products may belong to different groups at the same time, however, three types are usually distinguished:

• fastening;
• hook-shaped;
• loopback

The first type is universal, the second is designed for hanging objects, and the third is for catching something. In addition, these fasteners can be divided into the following main groups - with a wedge at the end and with a wedge in the form of a nut. Anchors are manufactured in fixed sizes - the smallest have a length of 50 mm and a diameter of 6-8 mm, the largest - up to 500 mm and a diameter of up to 22 mm.

Tip: the question of how to install an anchor can be solved very simply. To do this, you simply need to select the correct diameter of the hole - you need to drill with a drill of exactly the same size as the anchor itself - you can’t expect that a 12 mm bolt will hold in a 15 mm hole. It is also not advisable to wrap anything around the anchor, it does not make any sense - just insert it into the hole and tighten it with a screwdriver.

Dowels

These fasteners are also extremely popular in the modern construction market. They are necessary for high-quality fastening various objects and materials to solid structures. There are three types of dowels:

• metal ones are the most ancient. Can be used on almost all surfaces, but with a simple hammer it is problematic to score them, especially in hard materials– therefore, pneumatic, electric or cartridge pistols are more often used. Such dowels differ from each other only in diameter and length;
• installation ones are the most common today. They can be manufactured in two variations, which differ from each other in the shape of the plastic tip. In some cases they are mounted in a specially prepared chamber, but in others they are not (the plug has a mushroom-shaped shape). Such dowels are mounted using a hammer drill - a hole is made and then inserted into it plastic stopper, into which a steel nail is driven or screwed. If necessary, you can then very easily unscrew it thanks to the special thread. Depending on the diameter, dowels are 6.8 - 14 mm, and lengths - 30-300 mm;
• spacer (Bierbach dowel) - made of steel and demonstrate high performance characteristics for use in concrete bases. They consist of two wedges that are connected to each other in a movable way using a washer. Pre-mounted drilled holes, in which they are then wedged with one impact force of a hammer.

They are usually used for fastening in solid wall structures. The fixation of the dowel is based on the frictional force that occurs due to the spacer of the fastener during installation with the appearance of a holding force. The dowel can withstand increased static loads - when installed, the fasteners are destroyed during the pulling process.

The product itself is made of polymer materials. Their physical and mechanical characteristics can be greatly transformed, depending on various influences and conditions. These include, first of all, filler parameters, the ratio of components polymer material, properties of the binder. The disadvantages of polymer dowels include low heat resistance, a tendency to deform under load, and increased aging. Maximum loads can only withstand screws if they are correctly matched to the dowel. They must have all parameters (length and diameter) that fully correspond to the parameters of the dowels. The use of other fasteners places increased demands on the thread profile, since they determine the spacer effect. It is undesirable to use self-tapping screws and self-tapping screws to secure drywall.

Drywall fastening: molly

For high-quality fixation of gypsum board sheets, there is only one group of fasteners, which is called “molly”, received from the company that developed this fastener. It consists of two parts - an empty folding tube with special slots, a nut and a screw. As the screw is tightened, the tube is assembled and crimped on both sides of the gypsum board. There are two types of molly:

• metal;
• plastic.

The first type is the most reliable - it is installed using special pliers, and to install plastic ones, you need to pre-drill holes with a diameter of 8 mm, insert fasteners into them, and then tighten the screws. Using such elements, only light objects can be hung on drywall - if it is necessary to fix heavy ones, then embedded profiles should be provided.

Bolts

Bolts are fasteners cylindrical, which have a metric cylindrical external thread and a head that is designed for a nut. They make it possible to create connections using nuts or pre-made threaded holes in fixed parts. They are in form:

• stepped, in which the thread diameter is smaller than the diameter of the smooth part;
• foundation ones, which have a specially shaped head that helps secure equipment and units to the base;
• with a hexagon-shaped head for a wrench - this is the most common design option.

A bolt is inserted into a pre-prepared hole in the parts that need to be fastened, after which a nut is screwed onto the thread and the elements are tightened using wrench. The connection is fixed due to friction - but in order to transfer part of the loads to the bolt, it is necessary to ensure maximum precision in the production of the rod and the holes for it. To prevent deformation of parts, washers are installed under the bolt head and nuts. Bolts are always used in combination with nuts.

Nuts: types and principle of operation

Nuts are also a very popular type of fastener, which is distinguished by specially cut holes inside threaded connection. Galvanized products are the most widely used, and their shape can be completely different - hexagonal, round with notches, square, with protrusions for gripping with fingers. Main functional purpose Nuts are the connection of parts using bolts. They are:

• hexagonal;
• square;
• in the shape of a “lamb”;
• flanged with grooves for a cotter pin in the form of a cap;
• T-shaped, with special plastic inserts.

In addition, nuts are also divided into strength categories according to the types of bolts with which they are used.

Rivets

Combination type blind rivets consist of an aluminum body and a rod, which is made of galvanized steel. Such design feature is one of the most common and in demand today. Rivets are used to join two or more surfaces of thin sheets– with their help a permanent connection is created. Also on the modern market there are rivet nuts. These are fasteners widely used in electronics and mechanical engineering. They are necessary to create a threaded connection in metal materials or other thin surfaces with high strength.

Among the large selection of these fastening products, some of the most durable are threaded steel rivets. They are protected from corrosion by galvanizing. In design, such products differ from simple exhaust systems in that they can not only connect sheets of materials to each other, but also have an internal screw thread. They are mounted in hard to reach places, where it is impossible to reach with a riveter. Present on the modern market wide choose standard sizes, so choose them to solve the required technical problem is not difficult.

Use of screws, screws and other fasteners

In order for the screws to correctly perform the functions assigned to them, their sizes should be selected correctly. Screws are fasteners that are necessary for wood structures - their shaft tapers towards the end and acts as a drill. This type fasteners cannot be used like nails, driven into the surface - they must be completely twisted from beginning to end. Before using small screws, you should make a preliminary puncture, and large ones, a hole of a smaller diameter.

Screws are used to secure metal structures. Their heads allow high-quality pressing of the part to be joined, and the shape is selected in such a way as to make the process as easy as possible using a wrench or screwdriver. Depending on this, the screw heads can have different shapes:

• hexagonal;
• semicircular;
• secret.

They are always screwed into threaded holes, and in some cases they may have a design in which a hole is drilled at the end of the screw for cotter pins - wire rods with a semicircular cross-section. It is necessary in order to prevent spontaneous unscrewing of the fastening element.

If the screw is rusty, a hammer or special crimps can be used to remove it. Often help in this process can heat the nut using gas burner or blowtorch. If the use of open fire is prohibited for some reason, then a red-hot iron rod or soldering iron can be used.

Other products are also used for high-quality fasteners:

• washers are round plates made from cold rolled strip. They are used to increase strength bolted connections by placing it under the head of a bolt or under a nut;
• studs are cylindrical rods with external threads cut along the entire length or at the ends. Used in cases where more than one material in the connection does not have a thread;
• screws - rod fasteners with a conical point that have the property of creating new thread in plastic or wooden products.

On the market building materials there is very big choice fasteners. They must be selected in full accordance with technological features application and technical purposes, as well as operating conditions.

For use various connections Wood in the field of construction cannot be done not only without tools, but also without relevant experience. That is why inexperienced craftsmen do not always make such connections accurately. One of best options— professionals use various types of fasteners for the array, which are made of metal.

Many surviving architectural monuments made of wood were built without nails, using only an ax. This fact causes true pleasure to this day. However, centuries later, the fasteners made of metal, used to build solid wood buildings, have changed radically, and it is for this reason that today it makes no sense to repeat the experience of our ancestors.

It is preferable to build quickly and without difficulties. Let's talk in more detail about the fasteners offered by manufacturers, taking as an example details that make it possible to simplify as much as possible the connection of beams with floor joists or solid wall surfaces.

Perforated fasteners

When beams and also joists floor surface hidden in the interior space, they can be connected using beam shoes. This fastener for wood structures is suitable for fastening solid wood not just to wood, but also to concrete and brickwork. It is created from durable steel.

Manufacturers advise fastening such fasteners to the parts being connected with special screws, and in case of excessive load, or fixing to a stone material, use the holes for the necessary bolts. In addition to anchor shoes, today you can purchase special clamps and much more.

Tenon and groove

This galvanized wood fastener consists of a tongue and groove section that fit together to provide better transfer of horizontal as well as vertical forces.

The connection can be visible or hidden; for these purposes, the steel parts are recessed into special grooves in advance.

Three-dimensional slats

A modern Italian company produces fasteners, which are placed perpendicularly and vertically at an angle, by means of T-type slats created by extrusion from a high-strength steel alloy. They are produced in several modifications designed for different levels of loads.

The fastening system must be selected according to the size range of sections of the combined beams and the dynamic as well as static loads acting on them.

During the installation process, the slatted base is attached to the beam using self-tapping screws. Then a groove of the same size as the slatted shelf is created on the end part, attached to the base of the joist beam. If there is no perforation, the shelf is equipped with a log and the connection is secured using self-tapping screws.

Hidden details Hedgehog

These connectors are steel washers, the base of which is equipped with holes drilled under the slope. These holes are for self-tapping screws. In the center of the washer there is a threaded hole into which a pin is inserted. Its free end is threaded into a special hole and secured with reverse side beams as a part with an enclosed washer.

The created connection functions perfectly not only in pull-out, but also in shear. If there is excessive load in the area of ​​the end part of the joist, it is possible to install several elements at the same time.

Fasteners with complex threads

Unusual self-tapping screws that make it possible to save time, cash, since this option does not require metal parts. Self-tapping screws are equipped with threads, which help create a high degree of resistance when pulled out, and are also tightly screwed into an array, which completely changes their traditional functioning.

In this case, the work of the screws occurs exclusively by pulling out, which gives them the opportunity to absorb most of the forces that fall on the connection. So, you can fasten elements at an angle, combine parts, minimizing their deflection, as in the photo of wood fasteners below.

Special purpose self-tapping screws

Using similar elements, quite massive wooden crafts. The cap has milled ribs and is easily recessed into the product, while the tip is created like a drill. In the middle of the screw, the cutter makes a larger hole, helping to tighten the element as tightly as possible.

Self-tapping screw adjustable type will be useful for fastening door frames, window openings, solid wood lathing to wood, metal. The self-tapping screw is screwed directly into the box, as well as the wall surface located behind it, or the power part.

The self-tapping screw acts as a weather vane for high-quality fastening of solid wood cladding to a base made of steel. It has a tip in the form of a drill and wings placed above it to expand the hole in the tree.

When drilling metal products, the wings break. As a result, having made the carving in metal part, the self-tapping screw fits tightly to it, while the solid element is attracted by the head to the metal.

Photos of wooden fasteners

Fixed connections widely used in mechanical engineering are divided into two types: detachable (made mainly using threaded fasteners- bolts, screws, studs and nuts) and one-piece (performed various types rivets, welding, soldering, gluing).

Threaded and riveted connections are widely used in all branches of mechanical engineering, and they account for up to 35% of the total labor intensity of assembly work. The range of fasteners used is large and tends to grow. This is due to the fact that the creation of new progressive products, which are usually more expensive, does not exclude the possibility of using traditional cheap fasteners (bolts, screws, nuts, rivets, washers) in simple light-loaded units, guaranteeing the required consumer qualities cars For example, the US industry produces more than two million types of fasteners, including more than 50 thousand standard (in US terminology), totaling several billion dollars a year.

Classifier of state standards fasteners for general machine-building applications belongs to the GZ group, which includes the following classes: G31 - bolts; G32 - screws, studs; GZZ - nuts; G34 - rivets; G36 - washers, cotter pins; G37 - pins; G38 - other industrial hardware. Currently, many types of progressive fasteners that are not included in the Classifier of State Standards have been developed and mastered in various branches of the machine-building complex. The variety of fasteners based on structural, technological, functional and other characteristics makes it difficult to comprehensively classify and describe them. However, all fasteners can be divided into five groups. The basis of the classification is one of the most characteristic feature, which determined the name of each group, namely: fasteners for mass use; high-strength threaded fasteners; fasteners for one-sided installation and impactless riveting; fasteners for high-life and hermetic connections; fasteners for joining polymer composite materials.

The convention of the proposed classification is that each group has a certain range of fasteners that can be classified into another group. For example, in the group of fasteners for single-sided installation and non-impact riveting, some designs of bolt rivets are intended for high-life connections or for connections of composite materials. At the same time, each of the groups includes fasteners of several classes according to the Classifier of State Standards. For example, the group of high-strength fasteners includes classes of bolts, screws, nuts, and the group of high-resource fasteners includes classes of bolts, rivets, etc.

However, the proposed classification allows designers and technologists to relatively easily understand the wide variety of fasteners and take into account their specific features when designing and developing technological processes assembly of detachable and permanent connections, and will also provide assistance to specialists involved in the design and organization of specialized production of fasteners.

It is often very difficult to name a fastener correctly. What is this? Bolt or screw, anchor or dowel. Considering the wide variety of this class of products and the complexity of their correct names, we turn to GOST, which regulates names and terms.

Below are some of the most commonly used terms and definitions in accordance with GOST 27017-86 for fasteners and their structural elements.

	A fastener in the form of a rod with a male thread at one end and a head at the other, forming a connection by means of a nut or threaded hole in one of the products being connected.
	A fastener for forming a connection or fixation, made in the form of a rod with an external thread at one end and a structural element for transmitting torque at the other. Note: The structural element of the screw for transmitting torque can be a slotted head, a knurled head, or, in the absence of a head, a slot in the end of the rod.
	A fastener in the form of a rod with an external special thread, a threaded conical end and a head at the other end, forming a thread in the hole of the wooden or plastic product being connected. Note: The special thread has a triangular, pointed profile and a larger cavity width compared to the width of the tooth.
	A fastener in the form of a cylindrical rod with external threads at both ends or along the entire length of the rod.
	A fastener in the form of a cylindrical or conical rod for fixing products during assembly.
	A fastener with a threaded hole and a structural element for transmitting torque. Note: The structural element of the nut for transmitting torque can be a polyhedron, knurling on the side surface, end and radial holes, splines, etc.
	A fastener with a hole placed under a nut or the head of a bolt or screw to increase the bearing surface and (or) prevent them from self-unscrewing.
	A fastener in the form of a semicircular wire rod, folded in half to form a head.
	A fastener in the form of a smooth cylindrical rod with a head at one end, used to obtain a permanent connection due to the formation of a head at the other end of the rod by plastic deformation.
	A bolt whose diameter of the smooth part of the rod exceeds the nominal diameter of the thread.
	A bolt whose head is made in the form of a movable part of a hinge joint.
	A bolt, the diameter of the smooth part of the rod is determined from the condition of ensuring the operation of the shear connection.
	A bolt with a specially shaped head used to secure equipment to the foundation. Note: The special shape of the head can represent the spread tabs of the slotted part of the rod, the bent part of the rod, etc.
	A screw whose diameter of the smooth part of the shaft is less than the internal diameter of the thread.
	A screw that forms a special thread in a hole in one of the plastic or metal products being connected.
	Self-tapping screw with drill shaped end.
	A screw with a specially shaped end used to fix products relative to each other. Note: The special end shape can be cylindrical, conical, flat, etc.
	A cylindrical pin with a longitudinal groove along its length, made of spring steel.
	Hexagonal nut with radially located slots for a cotter pin on the side of one of the end surfaces.
	A hex nut, part of which is made in the form of a cylinder with radially located slots for a cotter pin.
	Nut with spherical and flat end surfaces and a blind threaded hole.
	A nut with flat protruding elements for transmitting torque.
	Washer with a flat supporting surface.
	A split round washer, the ends of which are located in different planes, which serves to prevent self-unscrewing of fasteners during its elastic deformation under load.
	A washer used to prevent self-unscrewing of fasteners using structural elements. Note: The structural elements of the washer are legs, toes, teeth, etc.
	Rivet with a tubular cross-section rod.
	A rivet, the end part of the rod of which has a tubular cross-section.

Elements of fasteners

Kernel. Part of a fastener that directly fits into the holes of the connected products or is screwed into the material of one of them.

Fastener head. Part of a fastener having a shaft that serves to transmit torque and/or form a bearing surface.

Bolt head. The smooth portion of a bolt's shank, cylindrical, oval, or square, directly adjacent to the head and used to center the bolt or prevent it from turning.

Fastener collar. A protrusion on the supporting surface of a multi-faceted nut, bolt or screw head, made in the shape of a cylinder or truncated cone diameter greater than the diameter of their circumscribed circle.

Support protrusion of a fastener. An annular projection on the bearing surface of a multi-faceted nut or bolt head, the diameter of which is less than the wrench size.

Note: The wrench size refers to the distance between the opposite edges of a multifaceted nut or bolt head, screw, measured in a plane normal to their axis.

Fastener slot. A specially shaped recess at the end of the head of a bolt, screw or screw, at the end of a set screw without a head, along a generatrix or at the end of a nut.

Note: The slot shape can be hexagonal, cross-shaped, through or non-through slot, etc.

Bolt spike. A protrusion on the supporting surface of the bolt head that serves to prevent it from turning.

Bolt lug. A protrusion on the supporting surface of the head and shank of a bolt, which serves to prevent it from turning.

Gimlet. The threaded, conical end of a screw used to cut threads into a piece of wood or plastic to form a joint.

GOST 27017-86 fully complies with the ISO 1891-79 standard and should be used in conjunction with GOST 11708-82 “Thread. Terms and Definitions". GOST 27017-86 establishes terms and definitions for fasteners for general engineering use. Standards establish only basic terms. Today, when new types of fasteners appear in Russia, there is a process of formation of terminology; strictly speaking, this is a constant process. The desire of market participants to avoid discrepancies in names is quite natural.